This is how I modified the code:

$.ctrl = function(key, callback, args) {
var isCtrl = false;
$(document).keydown(function(e) {
if(!args) args=[]; // IE barks when args is null

if(e.ctrlKey) isCtrl = true;
var kc = parseInt(key);
if((!isNaN(kc) && kc > 0 && e.keyCode == key || isNaN(kc) && e.keyCode == key.charCodeAt(0)) && isCtrl) {
callback.apply(this, args);
return false;
}
}).keyup(function(e) {
if(e.ctrlKey) isCtrl = false;
});
};

$.ctrl(45, function() { alert(‘custom functionality goes here’); return false; });